The invention relates to a catheter, in particular for endovascular applications, comprising a long and flexible, hollow, tubular body having an insertion end and a connection end intended to remain outside the body.
In the medical field it is known that there exists the need to carry out suitable procedures for the treatment of vessels which are obstructedxe2x80x94at least over part of their diameterxe2x80x94by constrictions, or so-called xe2x80x9cstenosesxe2x80x9d, arteriosclerotic plaques with or without superimposed thrombi, or the like, in order to restore the complete accessibility and functionality thereof. Said stenoses may hinder or even prevent the normal flow of substances which physiologically pass through the vessels. In particular in the case of the carotid artery, said stenoses may hinder or even prevent the normal flow of blood towards the organs in the head such as, for example, the brain and the eyes. Said stenoses may also release fragments of plaque or thrombi with the possibility of serious embolisms affecting the abovementioned organs.
Normally these types of pathologies are dealt with by means of external surgery. Said surgery involves the incision of the skin and the underlying layers and isolation of the section of artery affected by the stenosis; it also involves clamping the artery itself, which is performed upstream and downstream of the stenosis so as to block the circulation temporarily. In particular, in the case of the carotid artery, said clamping is normally performed upstream and downstream of the carotid bifurcation, i.e. on the common carotid, on the internal carotid and on the external carotid. At this point it is envisaged operating on the section affected by the stenosis using the appropriate procedures which envisage removal of the obstructing plaque through the opening of the artery section concerned, which is then carefully cleaned and sewn up again directly or by means of application of a prosthetic widening tissue (called xe2x80x9cpatchxe2x80x9d). The surgical method involves, however, closure of the section of the carotid artery operated on with interruption of the blood flow for a period of time of about 15-30 minutes. During this period of time, the flow of blood to the brain is compensated for by the flow coming from other arteries directed towards the brain.
In 10-15% of cases this compensation of the blood flow is not sufficient and, after just 9 minutes of clamping, serious damage to the brain may occur. To avoid this, it is necessary to carry out extremely rapid operations with the risk of imprecision, or apply special devices consisting of temporary bridges (or xe2x80x9cshuntsxe2x80x9d) which are applied downstream of the section of carotid artery which is obstructed. These devices, however, cause an obstruction in the operating zone and may cause complications and, for these reasons, are used only if absolutely necessary. In order to identify the cases where shunts are required, numerous systems have been developed for monitoring the state of the brain or the cerebral blood flow. These systems are not devoid of errors or inaccuracies, so that many surgeons use the method of brain monitoring while operating on the patient in the conscious state and under a local, anaesthetic. This method, which is the safest for avoiding brain damage during the operation, has the drawback that it subjects the patient to a great deal of stress and often is very painful, in particular in the case of patients with particular anatomical forms (xe2x80x9cbull neckxe2x80x9d) or who have carotids affected by lesions or carotid bifurcations which are situated very high in the neck. The operation also involves the possibility of damage to the nerves in the neck, in particular in the case of repeated operations or necks subjected to radiotherapy, with unpleasant post-operative consequences.
In view of the above situation, for several years now there has been the need to provide a new instrument for therapeutic treatment which allows treatment of pathologies such as those described or similar pathologies, using procedures which are less invasive or not invasive at all, in order to reduce as far as possible the risks for the patient, associated with a surgical operation. For this purpose, in about the year 1980, Matias was the first person to transfer the techniques of endoluminal dilation of the peripheral arteries to the carotid arteries. These techniques involve positioning a guide wire beyond the stenoses. A catheter equipped with an inflatable element (commonly called a xe2x80x9cballoonxe2x80x9d) is then passed along the guide wire and the inflatable element is expanded in the region of the stenosis in order to dilate it. This method has been successful, but also involves many complications due to thromboses or embolisms.
The results have improved with the use of elements, called xe2x80x9cstentsxe2x80x9d, which consist in tubular shaped meshwork structures which have the task of supporting the dilated section, holding in place the thrombus and plaque fragments. Despite this, the number of unsuccessful results have still been high. In order to avoid embolisms during the procedure, guide wires provided with a xe2x80x9cballoonxe2x80x9d to be applied inside the internal carotid artery, or a supporting catheter provided with an expandable element (or xe2x80x9cballoonxe2x80x9d) to be applied to the common carotid artery, have been developed. These methods, however, are unable to prevent possible embolisms during the endoluminal manoeuvre since they do not provide protection during the initial stages of insertion of the guide wires (xe2x80x9cTeronxe2x80x9d method) and moreover they do not exclude the flow towards the brain through the external carotid artery.
The object of the present invention is therefore that of providing a catheter which is able to overcome these drawbacks by means of occlusion or clamping involving the inflation of expandable elements (or xe2x80x9cballoonsxe2x80x9d) simultaneously inside the common carotid artery and inside the external carotid artery. This catheter must also have an operating channel which allows the stenotic artery sections to be dilated and the appropriate stents to be applied rapidly, sucking then inside the artery section concerned any embolism-producing material, thereby associating the safety of conventional surgery with the advantages of the endoluminal procedures.
The invention therefore has the aim of providing, by means of simple and low-cost measures, a catheter of the type described initially which allows:
exclusion of a section of a vessel from the blood flow, in order to block temporarily the circulation of the substances which physiologically pass through them, so as to be able to carry out any treatment or manoeuvre inside the said vessel section;
the abovementioned isolation and subsequent treatment using procedures which are invasive to a minimal degree or not at all, and in particular the possibility of insertion in loco by means of an extremely small incision inside an artery situated at a distance (such as, for example, the femoral artery);
elimination of the need for a surgical operation, thereby reducing the risks for the patient, said risks always being associated with treatment of the invasive type;
treatment of vessel sections which have undergone a previous surgical operation and/or reduction of the operating zone also in the case of a first operation;
provision of an instrument for treatment which is extremely simple to use;
reduction in the duration and the costs of the operation and the period of hospitalisation and convalescence of the patient, resulting in considerable savings in the associated maintenance costs.
The invention achieves the abovementioned objects by means of a catheter of the type described initially, comprising at the insertion end or distal end, at least two elements which are expandable/contractible by means of external operation.
Said expandable/contractible elements may be arranged at a distance from one another such that one is able to operate upstream and the other downstream of a given section of a vessel or two different adjacent vessel sections.
Said expandable/contractible elements may be adapted, with regard to their diameters in the expanded condition, to the diameters of the vessels inside which they are to be positioned, so as to occlude them entirely and block temporarily the blood circulation in the section or sections concerned.
Said expandable/contractible elements located at the insertion end may be inflated/deflated by means of supply and discharge ducts provided in the thickness of the catheter wall. This solution allows the diameter of the catheter to be limited, facilitating insertion of the latter, and avoids occupying the internal central luminal duct, or operating channel, which is intended to convey the appropriate treatment means.
The catheter may have a hollow tubular shape with a larger initial diameter provided externally, in particular at the distal end, with a first inflatable/deflatable element, operation of which is performed via one of the ducts provided within the thickness of the catheter.
At least one of the other ducts provided within the thickness of the catheter may extend, over a certain length, into a second section of the catheter, of smaller diameter, which extends from the distal end of the larger-diameter section and terminates in a second inflatable/deflatable element, operation of which is performed via said duct.
The catheter comprises a further duct in the wall thickness, which emerges at the tip of the entire catheter, namely at the distal end of the second smaller-diameter section. This duct has the function of conveying the guide wire.
The hollow larger-diameter catheter section has a further central duct with a diameter suitable for conveying treatment means necessary for operating in the vessel section or sections comprised between the two inflatable/deflatable elements. Said treatment means may consist in balloon or stent catheters both of the self-expanding type and the type expandable by means of inflation, in which case the stent may be located at the distal end of an additional catheter of a suitable diameter and introduced via the central duct of the catheter according to the invention, so as to reach the vessel section inside which it must be applied.
The section comprised between the two inflatable/deflatable elements may have a length of the order of between a few cm and about 10 cm, i.e. substantially equivalent to the longitudinal extension, for example, of stenoses in arterial vessels or the like or the section of a main vessel to be occluded and the first section of a bifurcation branch (as in the case of a common and external carotid), thus blocking any flow in the second dividing branch.
For particular applications, the two elements may be provided at distances different from those indicated above.
The catheter may have a first external larger diameter of the order of magnitude of about 12-13 French and in any case preferably not greater than 13-14 French (approximately 4 mm), while the second external smaller diameter may be of the order of magnitude of about 5 French (approximately 1.5 mm). For particular applications, diameters with measurements different from those indicated above may be envisaged.
The catheter may have, in the connection end or proximal end, an end-piece intended to remain outside the patient""s body. Said end-piece may be provided with tubular elements, which are preferably rigid or semi-rigid, having the function of providing a connection to the individual ducts.
The catheter according to the present invention may be used advantageously in particular in an endovascular system for the treatment of stenoses of the carotid, in order to isolate an artery section inside which a stenosis is present, so as to block temporarily the blood flow inside the said vessel section. Said system may comprise the following steps:
positioning of a guide wire so that, when passing in particular inside the common carotid, its distal end is arranged inside the internal carotid;
insertion of the catheter on the guide wire, through the respective duct provided in the thickness of the catheter wall;
positioning of the catheter so that the end of the smaller-diameter extension is arranged, with respect to the direction of the blood flow, in particular in the external carotid and the larger-diameter end is arranged in particular inside the common carotid;
inflation of the two expandable/contractible elements via the two respective ducts provided in the thickness of the catheter wall;
treatment of the stenosis in the internal carotid by means of insertion of the appropriate instruments for treatment (guides, balloon catheters, stents, aspirators, angioscopic instruments, IVUS, devices for thrombolysis, catheters for angiographic checks, etc.) through the central duct;
aspiration through the central duct 2 of possible residues deriving from catheter expansion;
deflation of the two expandable/contractible elements via the two respective ducts provided in the thickness of the catheter wall;
final monitoring;
extraction of the catheter and the guide wire.
All the abovementioned steps may be performed with continuous visual monitoring, thanks to one of the well-known existing techniques. In this connection, the tubular body of the catheter may comprise radiopaque markers for locating and identifying the said catheter.
As a result of the series of measures described above it is possible to provide, using simple and low-cost means, a catheter which allows:
isolation of a section of a vessel so as to prevent temporarily the flow of the substances which physiologically pass through it, so as to be able to carry out any treatment inside this vessel section;
the abovementioned isolation and subsequent treatment using procedures which are only slightly invasive or not at all invasive, and in particular the possibility of insertion in loco by means of an extremely small incision situated at a distance (such as for example the femoral artery);
elimination of the need for a surgical operation, thereby reducing the risks for the patient, said risks always being associated with treatment of the invasive type;
treatment of vessel sections which have undergone previous surgery and/or reduction of the operating zone also in the case of a first operation;
provision of an instrument for treatment which is extremely simple to use;
reduction in the duration and the costs of the operation and the period, of hospitalisation and convalescence of the patient, resulting in considerable savings in the associated maintenance costs.
The additional features and any improvements of the invention will be described in the sub-claims.